This invention relates to circuit card enclosures and, more particularly, to improved structure for mounting a circuit card to a back wall of such an enclosure.
Complex electronic systems typically include a rectilinear sheet metal enclosure for the circuit cards making up the electronic system. Usually, a backplane board (i.e., a particular form of circuit card) is supported along a back wall of the enclosure and card guides are provided on the top and bottom walls of the enclosure so that the circuit cards making up the electronic system can be slid into the enclosure for mating engagement with connectors provided on the backplane board. Conventionally, the circuit card enclosure is formed of sheet metal and standoffs formed directly on the back wall of the enclosure are used for mounting the backplane thereto. These standoffs typically require screws extending through appropriately located openings in the backplane board to secure the backplane board to the back wall. Such screws add parts cost to the system and sometimes add assembly costs because they can be difficult to secure because of obstructions or inconvenient standoff location in the enclosure. For example, when the backplane board is located relatively low along the back wall of the enclosure, it is often difficult to have sufficient clearance for a screwdriver. It would therefore be desirable to provide circuit card mounting structure which eliminates screws to reduce part and assembly costs and also simplifies the assembly, further reducing assembly costs.